fix: seal format default and bagged consitency check corner case

* fix: test helpers now default to producing v1 seals, but the version was
  not set.
* fix: the legacy consistency proof check accounts properly for the
  case where mmrsizeA == mmrsizeB

massifs/massifcontextverified.go

@@ -155,9 +155,7 @@ func (mc *MassifContext) verifyContext(
 	ctx context.Context, options ReaderOptions,
 ) (*VerifiedContext, error) {
 
-	var ok bool
 	var err error
-	var peaksB [][]byte
 
 	// This checks that any un-committed data is consistent with the latest seal available for the massif
 
@@ -171,6 +169,23 @@ func (mc *MassifContext) verifyContext(
 		return nil, err
 	}
 
+	if state.Version == int(MMRStateVersion1) {
+		return mc.verifyContextV1(msg, state, options)
+	}
+	return mc.verifyContextV0(msg, state, options)
+}
+
+func (mc *MassifContext) verifyContextV1(
+	msg *cose.CoseSign1Message, state MMRState, options ReaderOptions,
+) (*VerifiedContext, error) {
+	var ok bool
+	var err error
+	var peaksB [][]byte
+
+	if state.Version != int(MMRStateVersion1) {
+		return nil, fmt.Errorf("unsupported MMR state version %d", state.Version)
+	}
+
 	// get the peaks from the local store, we are checking the store against the
 	// latest additions. as we verify the signature below, any changes to the
 	// store will be caught.
@@ -179,21 +194,9 @@ func (mc *MassifContext) verifyContext(
 		return nil, err
 	}
 
-	// NOTICE: The verification uses the public key that is provided on the
-	// message.  If the caller wants to ensure the massif is signed by the
-	// expected key then they must obtain a copy of the public key from a source
-	// they trust and supply it as an option.
-	pubKeyProvider := cose.NewCWTPublicKeyProvider(msg)
-
-	if options.trustedSealerPubKey != nil {
-		var remotePub crypto.PublicKey
-		remotePub, _, err = pubKeyProvider.PublicKey()
-		if err != nil {
-			return nil, err
-		}
-		if !options.trustedSealerPubKey.Equal(remotePub) {
-			return nil, ErrRemoteSealKeyMatchFailed
-		}
+	pubKeyProvider, err := mc.sealPublicKeyProvider(msg, options)
+	if err != nil {
+		return nil, err
 	}
 
 	// Ensure the peaks we read from the store are the ones that were signed.
@@ -218,7 +221,7 @@ func (mc *MassifContext) verifyContext(
 			err, mc.Start.MassifIndex, mc.TenantIdentity)
 	}
 	if !ok {
-		// We don't expect false without error, but we
+		// We don't expect false without error.
 		return nil, fmt.Errorf("%w: failed to verify accumulator state massif %d for tenant %s",
 			mmr.ErrConsistencyCheck, mc.Start.MassifIndex, mc.TenantIdentity)
 	}
@@ -252,3 +255,30 @@ func (mc *MassifContext) verifyContext(
 		ConsistentRoots: peaksB,
 	}, nil
 }
+
+func (mc *MassifContext) sealPublicKeyProvider(
+	msg *cose.CoseSign1Message, options ReaderOptions,
+) (*cose.CWTPublicKeyProvider, error) {
+
+	var err error
+
+	// NOTICE: The verification uses the public key that is provided on the
+	// message.  If the caller wants to ensure the massif is signed by the
+	// expected key then they must obtain a copy of the public key from a source
+	// they trust and supply it as an option.
+	pubKeyProvider := cose.NewCWTPublicKeyProvider(msg)
+	if options.trustedSealerPubKey == nil {
+		return pubKeyProvider, nil
+	}
+
+	var remotePub crypto.PublicKey
+	remotePub, _, err = pubKeyProvider.PublicKey()
+	if err != nil {
+		return nil, err
+	}
+	if !options.trustedSealerPubKey.Equal(remotePub) {
+		return nil, ErrRemoteSealKeyMatchFailed
+	}
+	return pubKeyProvider, nil
+}
+

massifs/massifcontextverifiedv0.go

@@ -0,0 +1,89 @@
+package massifs
+
+import (
+	"crypto/sha256"
+	"fmt"
+
+	"github.com/datatrails/go-datatrails-common/cose"
+	"github.com/datatrails/go-datatrails-merklelog/mmr"
+)
+
+// verifyContextV0 reads and verifies the V0 seal, which will remain important
+// for replicas for a while.
+func (mc *MassifContext) verifyContextV0(
+	msg *cose.CoseSign1Message, state MMRState, options ReaderOptions,
+) (*VerifiedContext, error) {
+
+	var ok bool
+	var err error
+	var rootB []byte
+
+	if state.Version != int(MMRStateVersion0) {
+		return nil, fmt.Errorf("unsupported MMR state version %d", state.Version)
+	}
+
+	state.LegacySealRoot, err = mmr.GetRoot(state.MMRSize, mc, sha256.New())
+	pubKeyProvider, err := mc.sealPublicKeyProvider(msg, options)
+	if err != nil {
+		return nil, err
+	}
+
+	err = VerifySignedCheckPoint(
+		*options.codec, pubKeyProvider, msg, state, nil,
+	)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"%w: failed to verify seal for massif %d for tenant %s: %v",
+			ErrSealVerifyFailed, mc.Start.MassifIndex, mc.TenantIdentity, err)
+	}
+	cp, err := mmr.IndexConsistencyProofBagged(
+		state.MMRSize, mc.RangeCount(), mc, sha256.New())
+	if err != nil {
+		return nil, fmt.Errorf(
+			"%w: error creating bagged consistency proof from %d for massif %d, for tenant %s",
+			err, state.MMRSize, mc.Start.MassifIndex, mc.TenantIdentity)
+	}
+
+	ok, rootB, err = mmr.CheckConsistencyBagged(mc, sha256.New(), cp, state.LegacySealRoot)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"%w: error verifying bagged consistency proof from %d for massif %d, for tenant %s",
+			err, state.MMRSize, mc.Start.MassifIndex, mc.TenantIdentity)
+	}
+	if !ok {
+		// We don't expect false without error, but we
+		return nil, fmt.Errorf("%w: failed to verify bagged state for massif %d for tenant %s",
+			mmr.ErrConsistencyCheck, mc.Start.MassifIndex, mc.TenantIdentity)
+	}
+	// If the caller has provided a trusted base state, also verify against
+	// that. Typically this is used for 3d party verification, the 3rd party has
+	// saved a previously verified state in a local store, and they want to
+	// check the remote log is consistent with the log portion they have locally
+	// before replicating the new data.
+	if options.trustedBaseState != nil {
+
+		cp, err := mmr.IndexConsistencyProofBagged(
+			state.MMRSize, mc.RangeCount(), mc, sha256.New())
+		if err != nil {
+			return nil, fmt.Errorf(
+				"%w: error checking consistency with trusted base state from %d for tenant %s",
+				err, options.trustedBaseState.MMRSize, mc.TenantIdentity)
+		}
+
+		ok, _, err = mmr.CheckConsistencyBagged(mc, sha256.New(), cp, options.trustedBaseState.LegacySealRoot)
+		if err != nil {
+			return nil, err
+		}
+		if !ok {
+			return nil, fmt.Errorf(
+				"%w: the accumulator produced for the trusted base state doesn't match the root produced for the seal state fetched from the log",
+				mmr.ErrConsistencyCheck)
+		}
+	}
+	return &VerifiedContext{
+		MassifContext:   *mc,
+		Sign1Message:    *msg,
+		MMRState:        state,
+		ConsistentRoots: [][]byte{rootB},
+	}, nil
+}

massifs/testcommitter.go

@@ -94,6 +94,7 @@ func (c *TestMinimalCommitter) ContextCommitted(ctx context.Context, tenantIdent
 	}
 
 	state := MMRState{
+		Version: int(MMRStateVersion1),
 		MMRSize:         mmrSize,
 		Peaks:           peaks,
 		Timestamp:       time.Now().UnixMilli(),

mmr/verifyconsistencybagged.go

@@ -22,26 +22,25 @@ func VerifyConsistencyBagged(
 	hasher hash.Hash, peakHashesA [][]byte,
 	proof ConsistencyProof, rootA []byte, rootB []byte) bool {
 
-	// A zero length path not valid, even in the case where the mmr's are
-	// identical (root a == root b)
-	if len(proof.PathBagged) == 0 {
+	// There must be something to prove
+	if len(peakHashesA) == 0 {
 		return false
 	}
 
-	// There must be something to prove
-	if len(peakHashesA) == 0 {
+	// Check the peakHashesA, which will have been retrieved from the updated
+	// log, recreate rootA. rootA should have come from a previous Merkle
+	// Signed Root.
+	if !bytes.Equal(HashPeaksRHS(hasher, peakHashesA), rootA) {
 		return false
 	}
 
 	// Catch the case where mmr b is exactly mmr a
-	if bytes.Equal(rootA, rootB) {
+	if len(proof.PathBagged) == 0 && bytes.Equal(rootA, rootB) {
 		return true
 	}
 
-	// Check the peakHashesA, which will have been retrieved from the updated
-	// log, recreate rootA. rootA should have come from a previous Merkle
-	// Signed Root.
-	if !bytes.Equal(HashPeaksRHS(hasher, peakHashesA), rootA) {
+	// Otherwise, s zero length path not valid
+	if len(proof.PathBagged) == 0 {
 		return false
 	}